Income Taxes - Income Tax Benefit/(Provision) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Current - Federal	$ (2)	$ (9)	$ 148
Current - State	(1)	(1)	(7)
Deferred - Federal	131	170	1,835
Deferred - State	22	(39)	23
Current - Outside of the U.S.	(7)	(9)	(4)
Deferred - Outside of the U.S.	(2)	9	0
Income tax benefit	$ 141	$ 121	$ 1,995